Type of Document	Master's Thesis
Author	Hall, Ellen L.
URN	etd-09182008-063530
Title	Pesticide distribution in water, sediment, and fish of the Occoquan Watershed
Degree	Master of Science
Department	Environmental Engineering
Advisory Committee	Advisor Name Title Dietrich, Andrea M. Committee Chair Godrej, Adil N. Committee Member Grizzard, Thomas J. Committee Member
Keywords	pesticides monitoring
Date of Defense	1996-04-25
Availability	restricted
Abstract About 50 synthetic organic chemicals (SOCs), including pesticides and polyaromatic hydrocarbons (PAHs), have been identified as possible contaminants in the Occoquan Watershed. Since 1982, water, sediment, and fish samples have been collected from the streams and reservoirs of the watershed 2-4 times per year. The Occoquan Watershed Monitoring Laboratory (OWML) collected samples and analyzed for a targeted set of compounds. Beginning in 1993, new SOC screening methods consisting of solid-phase extraction (SPE) followed by gas chromatography with mass spectrometric detection (GC/MS) were developed for water and sediment samples. A similar method for fish tissue was developed in this study using methanol extraction with C-18 and alumina SPE cleanup. Method detection limits (MDLs) ranged from 0.03-0.37 mg/kg wet weight and recoveries in matrix spikes ranged from 15-92%. Very few SOCs in OWML's database were found at levels above method detection limits. In water, atrazine was the most commonly detected compound (87 detections out of 610 samples analyzed). It was also found in 8 sediment samples and 1 fish organ sample. Atrazine concentrations were highest in the spring; summer provided the most frequent detections. Detections occurred at multiple locations during the same sampling period; stations furthest west (nearest to agricultural areas) tended to show the highest values. Rainfall events were associated with 23% of atrazine detections. The raw and finished water samples from the two water treatment plants in the basin showed that the average atrazine removal by conventional treatment was 37%.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access  LD5655.V855_1996.H355.pdf 3.44 Mb 00:15:54 00:08:10 00:07:09 00:03:34 00:00:18 next to an author's name indicates that all files or directories associated with their ETD are accessible from the Virginia Tech campus network only.

If you have questions or technical problems, please Contact DLA.